Optical deflector having tapered aperture stop, light scanning apparatus and scanning type image display apparatus using same

Abstract

An optical deflector is disclosed which is capable of preventing unnecessary reflection by a member disposed behind a reflecting portion. The optical deflector includes a substrate portion, a reflecting portion can swing about a swinging motion axis with respect to the substrate portion, and an aperture stop portion which includes an aperture and blocks at least part of a light beam other than a light beam entering the aperture among an incident luminous flux to the optical deflector. The aperture allows passage of the incident luminous flux toward the reflecting portion and that of an emergent luminous flux reflected by the reflecting portion. At least part of an aperture rim of the aperture stop portion has a shape that makes the width of the aperture narrower from a light-beam-incoming side toward a reflecting portion side.

1. An optical deflector comprising:
 a substrate portion; 
 a reflecting surface which is swingable about a swinging motion axis with respect to the substrate portion, wherein the reflecting surface is swingable about the swinging motion axis from a neutral static state of the reflecting surface; and 
 an aperture stop portion which includes an aperture and which blocks at least part of a light beam other than a light beam entering the aperture, among an incident luminous flux to the optical deflector, the aperture allowing passage of the light beam entering toward the reflecting surface and that of an emergent luminous flux reflected by the reflecting surface, 
 wherein at least part of an aperture rim of the aperture stop portion has a tapered surface such that the width of the aperture becomes narrower from a light-beam-incoming side toward a reflecting surface side, and 
 wherein an angle between the tapered surface and a central axis of the aperture is greater than a maximum exit angle between the emergent luminous flux reflected by the reflecting surface and the central axis of the aperture, and 
 wherein the aperture stop portion has a front surface which is different from the tapered surface, the front surface being a light-beam-incoming side of the aperture stop portion, and the front surface being inclined with respect to the reflecting surface when the reflecting surface is in the neutral static state. 
 
     
     
       2. The optical deflector according to  claim 1 , wherein the light-beam-incoming side surface has a shape which reflects the light beam impinging thereon among the incident luminous flux in a direction different from an outgoing angular range of the emergent luminous flux reflected by the reflecting surface. 
     
     
       3. A light scanning apparatus comprising:
 a light source; and 
 the optical deflector according to  claim 1 , which scans a light beam from the light source. 
 
     
     
       4. A scanning type image display apparatus comprising:
 a light source; and 
 the optical deflector according to  claim 1 , 
 wherein the apparatus scans a light beam from the light source with the optical deflector to display an image. 
 
     
     
       5. An image display system comprising:
 the scanning type image display apparatus according to  claim 4 ; and 
 an image supply apparatus which supplies image information to the image display apparatus. 
 
     
     
       6. The optical deflector according to  claim 1 , wherein an inclination angle D of the inclined front surface is larger than a maximum swinging angle of the reflecting surface about its swinging motion axis. 
     
     
       7. The optical deflector of  claim 1 , wherein the front surface is inclined such that the aperture stop portion has a thicker end and a thinner end, and
 wherein width of the aperture as measured at the front surface is wider towards the thicker end of the aperture stop portion than towards the thinner end thereof.